the effect of various plastic materials on the flavor and shelf life of pasteurized milk and ultra pasteurized milk

as milk is a liquid compound, it needs containers at every stages of movement. the first significant development in milk packaging created at the end of nineteenth century. the flavor changes and shelf life of pasteurized milk and ultra pasteurized milk are affected by processing conditions, packaging materials and microbial growth. off-flavor is an effective factor on reduction of milk quality. off-flavor development in milk depends on fat content, light and oxygen permeation, container size and packaging materials. clear polyethylene terphthalate bottles are suitable for pasteurized milk which is consumed faster, but they aren’t suitable for ultra-pasteurized milk that needs long shelf life unless we create sufficient light barrier in pet bottles in order to avoid photo-oxidation off - flavor. one type of suitable packaging for pasteurized milk and ultra-pasteurized milk is a packaging which is laminated cardboard with barrier properties and are able to maintain the natural milk’s flavor such as: (ldpe /card board /ldpe /pp, ldpe /cardboard /ldpe /evoh /ldpe, and pe /card board /pe /al-foi l/pe), the cardboard must be suitable for milk packaging and have good barrier properties. multilayer flexible packagings are produced by co-extrusion processes and can protect products during shipping, display, and storage. these packagings are the combining of two or more layers into a composite web. lldpe or it’s combination with ldpe is used for milk pouches. if oxygen barrier is required for long shelf life, then poly-amid could be used.